These components, when found to occur commonly, are what PEC
theorists mean by the term abilities.
Ability measurement is more advantageous than skill measure-
ment in terms of time, effort, cost, and ease of record keeping, as well
as the amount of information that is implicit. For example, in career
counseling, the use of ability measurement enables the assessment of
a client’s potential for skills that the client does not have, not just
the ones the client has. One does not have to be a captive of the
skills one has; with ability measurement, one can explore one’s
potential for skills that one does not have, and then develop them!
Needs
Needs are P’s requirements; therefore, the most direct way to mea-
sure needs would be to ask P about them. There are several ways to
ask about P’s needs, one of which is to use a standardized self-report
questionnaire. Most such questionnaires in current use are cast in a
rating format, to take advantage of the well-developed technology
of rating (see, for example, Guilford, 1954, or Landy & Farr, 1980).
This technology can be used to maximize the accuracy of self-dis-
closure (validity) and to minimize the errors that can distort self-
disclosure (reliability).
Each need can be measured by one question (item) or several
items. Item scores can be aggregated to yield need scale scores. Ag-
gregation can be done by using any of a number of methods, known
as scaling methods (Dawis, 2000). Most of the published need scales
are of the self-report–questionnaire variety.
Needs are requirements for reinforcers, which have two sources:
E and P (the environment and the self). Because P is a social being,
one class of environmental reinforcers exerts a particularly strong
influence on P: social reinforcers. Thus reinforcers can be classified
into three groups according to source: (1) environmental, (2) social,
and (3) self.
In principle, each reinforcer would define a need and, therefore,
would require its own need scale. Given this, the number of needs
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